Methods based on liquid-crystal physics are being developed to orient photoreceptor membrane isolated from retinal rod outer segments into liquid-crystal films. These films can be used in biophysical studies to obtain information about the structure and function of rhodopsin, the membrane protein directly involved as a trigger in visual transduction. Specific studies involve the use of resonance Raman light scattering and polarized infrared spectroscopy. Purple membrane isolated from the bacterium, Halobium halobacterium is also being studied as a model for proton transport and energy transduction in biological membranes.